I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far. I
would really appreciate any pointers to either a circuit I could
breadboard or a canned solution. I was thinking I'd go commercial and
add some gain for a better look the narrow bandwidths used in
communications gear but anything that will work with normal HT's will
solve my problem. Thanks for any help!

On Wed, 28 Jan 2015, nothermark wrote:

I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far. I
would really appreciate any pointers to either a circuit I could
breadboard or a canned solution. I was thinking I'd go commercial and
add some gain for a better look the narrow bandwidths used in
communications gear but anything that will work with normal HT's will
solve my problem. Thanks for any help!

Find an older cordless phone. Most converted to 10.7MHz, and then again
to 455KHz. Often a Motorola IC to do the IF strip. Older would mean
easier to work with components, ones that can be identified. If you're
lucky, you can extract the circuitry intact, if not just pull the parts
and build on a new board. You'll get all you need, including a crystal to
convert from 10.7MHz to 455KHz.

Baby monitors used this scheme, at least some of them. 49MHz superhet
walkie talkies did too. The cellphones I've taken apart generally go to a
higher IF around 45MHz or so, and then down to 455KHz, so those are out.

Just about any ham FM rig used 10.7 and 455KHz, as did many monitor
receivers and scanners, so find scrapped units and transplant their IF
circuitry.

Michael

nothermark wrote:
I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy.

I assume you mean the IC-R7100, not the IC-7100 which is a completely
different thing.

I have an IC-R7100 and I added a 9-pin DB connector and put the direct
detector outputs on it for different purposes. It was not that difficult,
if I remember well.

"nothermark" wrote in message
...
I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far. I
would really appreciate any pointers to either a circuit I could
breadboard or a canned solution. I was thinking I'd go commercial and
add some gain for a better look the narrow bandwidths used in
communications gear but anything that will work with normal HT's will
solve my problem. Thanks for any help!

If just for a short time, just hook the scope to any audio point before the
voulme control. There may be a monitor output already that you can use.
You can then calibrate the devisions on the scope against a known source.
While not real good and varies with the frequency of the audio source, just
hook the scope across the speaker or plug in an external speaker. Youjust
have to set the volume at one point and not change it from the calibration
point you use.

If you can find an old scanner that has a true descriminator output instead
of the phase detector types, then it is easy. Hook a DC scope to that point
and fine a transmitter that has 1 khz steps . Go up and down one 1 khz at a
time and see where the trace goes. At each point will be the 1 khz steps.

On Wed, 28 Jan 2015 18:17:08 -0500, "Ralph Mowery"
wrote:


"nothermark" wrote in message
.. .
I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far. I
would really appreciate any pointers to either a circuit I could
breadboard or a canned solution. I was thinking I'd go commercial and
add some gain for a better look the narrow bandwidths used in
communications gear but anything that will work with normal HT's will
solve my problem. Thanks for any help!

If just for a short time, just hook the scope to any audio point before the
voulme control. There may be a monitor output already that you can use.
You can then calibrate the devisions on the scope against a known source.
While not real good and varies with the frequency of the audio source, just
hook the scope across the speaker or plug in an external speaker. Youjust
have to set the volume at one point and not change it from the calibration
point you use.

If you can find an old scanner that has a true descriminator output instead
of the phase detector types, then it is easy. Hook a DC scope to that point
and fine a transmitter that has 1 khz steps . Go up and down one 1 khz at a
time and see where the trace goes. At each point will be the 1 khz steps.

Hmmm, had not thought about that as I am also looking for a deal on a
signal generator. Come to think of it a 1 KHz shift between the
receiver and a transmitter will look like 1 Khz of deviation....

"nothermark" wrote in message
...

If you can find an old scanner that has a true descriminator output
instead
of the phase detector types, then it is easy. Hook a DC scope to that
point
and fine a transmitter that has 1 khz steps . Go up and down one 1 khz at
a
time and see where the trace goes. At each point will be the 1 khz steps.

Hmmm, had not thought about that as I am also looking for a deal on a
signal generator. Come to think of it a 1 KHz shift between the
receiver and a transmitter will look like 1 Khz of deviation....

I have done that many years ago when I could not afford very good test
equipment. I did have a frequency counter that was halfway decent and an
inexpensive scope and multimeter. Had to learn how to do things to get by
with. Took a lot of time to do simple things, but I learned a lot in the
process.

Yes, if you have a true discriminator and a DC coupled scope the shift of an
unmodulated carrier will look like the deviation.

In article ,
nothermark wrote:

I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far.

There was a pretty simple circuit shown in the old ARRL VHF Manual.
I'll see if I can pull out copy and scan it.

On Wed, 28 Jan 2015, Dave Platt wrote:


In article ,
nothermark wrote:

I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far.

There was a pretty simple circuit shown in the old ARRL VHF Manual.
I'll see if I can pull out copy and scan it.


Except they don't give much output at 10.7MHz, a pulse counting circuit
would be simple. Those seemed to get a lot of travel for novelty forty
years ago. They'd use logic ICs to amplify and limit the IF signal, then
a divider to get it down to a lower frequency where the pulse counting
could happen (the logic being kind of slow back then so it didn't work
well at 10.7MHz). Put it through a 10.7MHz ceramic filter from an FM
broadcast band receiver to limit bandwidth, mix it down to a lower
frequency (if the amplification and limiting is at 10.7MHz, a digital
mixer would work) then the pulse counting detector. Not unlike that
classic FM broadcast receiver in the GE Transistor Manual, a tunnel diode
mixer/oscillator and an untuned IF strip around 200KHz, then a pulse
counting detector. The concept is like those analog "frequency counters"
that were in the magazines at one point.

Michael

In article le.org,
Michael Black wrote:
On Wed, 28 Jan 2015, Dave Platt wrote:


In article ,
nothermark wrote:

I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far.

There was a pretty simple circuit shown in the old ARRL VHF Manual.
I'll see if I can pull out copy and scan it.


Except they don't give much output at 10.7MHz, a pulse counting circuit
would be simple. Those seemed to get a lot of travel for novelty forty
years ago. They'd use logic ICs to amplify and limit the IF signal, then
a divider to get it down to a lower frequency where the pulse counting
could happen (the logic being kind of slow back then so it didn't work
well at 10.7MHz).

Pulse-counting discriminators were fairly popular in some of the
high-end FM broadcast-music tuners in the 80s and 90s, I believe,
due to their high linearity and low distortion.

I found that circuit from the ARRL "FM and Repeaters" manual (1972
edition) I remembered. Unfortunately it doesn't include the FM
detector... it assumes that output is available directly from the
discriminator. It's just a fairly simple peak detector and meter,
which they suggest to calibrate via the Bessel method. Nothermark,
email me directly if you'd like a copy.

As to doing the FM detection/discrimination: there are probably still
"FM detector on a chip" ICs available today: OnSemi LA1225, NJM
2549/2550, and so forth. Hardest part is probably chasing down a
coil.

You could try using a ham radio which has a "packet data" jack... the
audio signal which comes out of this is often a fairly direct,
non-equalized version of the discriminator output (since this is what
a 9600-baud packet decoder wants to see).

nothermark wrote:
On Wed, 28 Jan 2015 18:17:08 -0500, "Ralph Mowery"
wrote:


"nothermark" wrote in message
. ..
I need a simple poor ham's deviation meter. That got me looking at
the IC-7100 receiver sitting in my shack. I could get to the
discriminators but it would be a bit messy. OTOH it has a 10.7 MHz IF
output I could add an amplifier and detector to and feed that to my
O'scope to do what I want for long enough to sort out some problems.
That got me looking for a simple detector circuit. No joy so far. I
would really appreciate any pointers to either a circuit I could
breadboard or a canned solution. I was thinking I'd go commercial and
add some gain for a better look the narrow bandwidths used in
communications gear but anything that will work with normal HT's will
solve my problem. Thanks for any help!

If just for a short time, just hook the scope to any audio point before the
voulme control. There may be a monitor output already that you can use.
You can then calibrate the devisions on the scope against a known source.
While not real good and varies with the frequency of the audio source, just
hook the scope across the speaker or plug in an external speaker. Youjust
have to set the volume at one point and not change it from the calibration
point you use.

If you can find an old scanner that has a true descriminator output instead
of the phase detector types, then it is easy. Hook a DC scope to that point
and fine a transmitter that has 1 khz steps . Go up and down one 1 khz at a
time and see where the trace goes. At each point will be the 1 khz steps.

Hmmm, had not thought about that as I am also looking for a deal on a
signal generator. Come to think of it a 1 KHz shift between the
receiver and a transmitter will look like 1 Khz of deviation....

Of course in these days you can use an RTL2830 DVB-T stick as a measurement
device (with some software like SDR#)

For $10 you will have a spectrum analyzer, measurement receiver and
deviation meter, without using your receiver or scope.